Studies have shown that certain anti-HIV medications can cause a number of side effects, including high blood sugar (resulting from the body's failure to use insulin), high insulin, and excess fat build-up in the abdominal area. These side effects are known to increase the risk of heart disease. Metformin and rosiglitazone are 2 drugs that have been shown to lower insulin resistance and lessen abdominal fat in patients who are not HIV-infected. This study will investigate the use of these drugs in HIV-infected patients.